1. Field of the Disclosure
The present disclosure relates to a transmission apparatus and a corresponding transmission method for transmitting signals in a multi carrier transmission system. Further, the present disclosure relates to a receiving apparatus and a corresponding receiving method for receiving signals in a multi carrier transmission system. Still further, the present disclosure relates to a multi carrier signal transmission system and a computer readable non-transitory medium.
2. Description of Related Art
Digital signals are transmitted in applications such as digital television broadcasting. Standards such as the so-called DVB standards have existed since the 1990s, and provide a range of different modulation schemes such as quadrature amplitude modulation (QAM) or orthogonal frequency division multiplex (OFDM) schemes for broadcast services, along with formats for the transmission of accompanying control data and metadata. These standards define both the radio frequency (RF) techniques used to carry the data and the way in which the data representing different broadcast services is organised into packets and streams for transmission.
The DVB standards are described extensively elsewhere, so only a brief summary will now be given, with reference to the standards relating to the transmission of broadcast cable services, although it will of course be appreciated that similar considerations can apply to (for example) digital satellite services and terrestrial broadcast services.
In basic terms, the video data, audio data and accompanying data corresponding to a broadcast programme are multiplexed into an MPEG-2 Programme Stream (PS). One or more PSs are multiplexed to form a transport stream (TS) formed as a sequence of fixed length data packets. The bit rate of the TS can range between about 6 Mbit/s and 84 Mbit/s depending on parameters such as the modulation scheme in use (16QAM to 4096QAM for example) and the bandwidth of the broadcast channel which will be used to carry the TS.
With current technology, one broadcast channel (with a bandwidth of a few MHz—up to 8 MHz) carries one TS. The TS includes packetised programme data (video, audio etc.) and packetised control data defining the different programmes carried by that TS (so called PSI/SI data). As elementary part of the PSI/SI data a so-called network information table (NIT) is also carried, which provides information about the physical network, such as channel frequencies, service originator and service name. Those details are particularly described in, Digital Video Broadcasting (DVB); Specification for Service Information (SI) in DVB systems—DVB Document A38, January 2011. Latest members of DVB's second generation physical standards such as DVB-C2 (as described in “Digital Video Broadcasting (DVB); Implementation Guidelines for a second generation digital cable transmission system (DVB-C2)—DVB document A147, November 2010”) and DVB-T2 overcome the limit of mapping one TS to one physical layer by use of the so-called PLP (Physical Layer Pipe) approach, i.e. one physical layer signal typically contains more than one data stream (TSs).
EP 2131521 A1 and EP 2131522 A1 disclose a digital signal transmitter in which multiple data streams are each transmitted by modulation of a respective frequency band within one of a group of frequency channels, the frequency bands each occupying no more than a predetermined maximum bandwidth less than or equal to the channel width. The transmitter comprises means for transmitting at respective frequency positions within each frequency channel, one or more instances of band information defining the frequency bands corresponding to all of the data streams carried within that frequency channel, the one or more instances being arranged so that any portion of the frequency channel equal in extent to the predetermined maximum bandwidth includes at least one instance of the band information. Further, a corresponding digital signal receiver is disclosed.
There is a growing demand not only for more digital television services but also for higher quality (in terms of picture and audio resolution) services. This demand imposes pressure on the digital payload carried by each channel. It is a constant aim to use the available broadcast spectrum efficiently and flexibly.
The “background” description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventor(s), to the extent it is described in this background section, as well as aspects of the description which may not otherwise qualify as prior art at the time of filing, are neither expressly or impliedly admitted as prior art against the present disclosure.